What started as a steering of stimulus money to a solar-paneling firm run by an Obama donor yesterday became a Capitol Hill scene that evoked memories of 1950s hearings into mob domination of organized labor.

Solyndra CEO Brian Harrison and chief financial officer Bill Stover both invoked Fifth Amendment protections against self-incrimination Friday in their appearance before the House Energy and Commerce Committee; they refused to testify despite previously having said they would.

Solyndra filed for bankruptcy earlier this month, with taxpayers losing out on a $535 million federal loan guarantee. The FBI and the Energy Department raided Solyndra’s Silicon Valley offices days later.

Congress is examining why the loan guarantees were approved despite the Bush administration’s refusal to support the same action in January 2009.

The committee is also exploring whether the administration violated the law by restructuring Solyndra’s loan last February to favor private investors over taxpayers in case the company were to default.

Legally speaking, Harrison and Stover have every right to decline to testify.

But that’s a political problem for the White House, given that President Obama visited Solyndra last year and hailed it as a “true engine of economic growth.”

More significantly, the image of individuals taking the Fifth before Congress is powerful — and can shift public opinion.

In the late ’50s, Sen. John McClellan’s Select Committee on Improper Activities in Labor and Management, with Bobby Kennedy as chief counsel and investigator, shined a powerful light on organized labor.

The committee’s investigation of the corruption-filled Teamsters led — after several attempts — to the conviction of Jimmy Hoffa on jury-tampering and conspiracy.

By the time the committee closed up shop in March 1960, some 343 of 1,526 witnesses had taken the Fifth — and labor never regained its reputation.

Solyndra’s collapse might just have been a bankruptcy driven by poor decisions in a bad economy. But the image of Obama supporters from a favored industry refusing to testify before Congress will linger.